LXR linux/arch/um/sys-x86

   1/*
   2 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3 * Copyright 2003 PathScale, Inc.
   4 *
   5 * Licensed under the GPL
   6 */
   7
   8#include "linux/linkage.h"
   9#include "linux/personality.h"
  10#include "linux/utsname.h"
  11#include "asm/prctl.h" /* XXX This should get the constants from libc */
  12#include "asm/uaccess.h"
  13#include "os.h"
  14
  15asmlinkage long sys_uname64(struct new_utsname __user * name)
  16{
  17        int err;
  18
  19        down_read(&uts_sem);
  20        err = copy_to_user(name, utsname(), sizeof (*name));
  21        up_read(&uts_sem);
  22
  23        if (personality(current->personality) == PER_LINUX32)
  24                err |= copy_to_user(&name->machine, "i686", 5);
  25
  26        return err ? -EFAULT : 0;
  27}
  28
  29long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
  30{
  31        unsigned long *ptr = addr, tmp;
  32        long ret;
  33        int pid = task->mm->context.id.u.pid;
  34
  35        /*
  36         * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
  37         * be safe), we need to call arch_prctl on the host because
  38         * setting %fs may result in something else happening (like a
  39         * GDT or thread.fs being set instead).  So, we let the host
  40         * fiddle the registers and thread struct and restore the
  41         * registers afterwards.
  42         *
  43         * So, the saved registers are stored to the process (this
  44         * needed because a stub may have been the last thing to run),
  45         * arch_prctl is run on the host, then the registers are read
  46         * back.
  47         */
  48        switch (code) {
  49        case ARCH_SET_FS:
  50        case ARCH_SET_GS:
  51                ret = restore_registers(pid, &current->thread.regs.regs);
  52                if (ret)
  53                        return ret;
  54                break;
  55        case ARCH_GET_FS:
  56        case ARCH_GET_GS:
  57                /*
  58                 * With these two, we read to a local pointer and
  59                 * put_user it to the userspace pointer that we were
  60                 * given.  If addr isn't valid (because it hasn't been
  61                 * faulted in or is just bogus), we want put_user to
  62                 * fault it in (or return -EFAULT) instead of having
  63                 * the host return -EFAULT.
  64                 */
  65                ptr = &tmp;
  66        }
  67
  68        ret = os_arch_prctl(pid, code, ptr);
  69        if (ret)
  70                return ret;
  71
  72        switch (code) {
  73        case ARCH_SET_FS:
  74                current->thread.arch.fs = (unsigned long) ptr;
  75                ret = save_registers(pid, &current->thread.regs.regs);
  76                break;
  77        case ARCH_SET_GS:
  78                ret = save_registers(pid, &current->thread.regs.regs);
  79                break;
  80        case ARCH_GET_FS:
  81                ret = put_user(tmp, addr);
  82                break;
  83        case ARCH_GET_GS:
  84                ret = put_user(tmp, addr);
  85                break;
  86        }
  87
  88        return ret;
  89}
  90
  91long sys_arch_prctl(int code, unsigned long addr)
  92{
  93        return arch_prctl(current, code, (unsigned long __user *) addr);
  94}
  95
  96long sys_clone(unsigned long clone_flags, unsigned long newsp,
  97               void __user *parent_tid, void __user *child_tid)
  98{
  99        long ret;
 100
 101        if (!newsp)
 102                newsp = UPT_SP(&current->thread.regs.regs);
 103        current->thread.forking = 1;
 104        ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
 105                      child_tid);
 106        current->thread.forking = 0;
 107        return ret;
 108}
 109
 110void arch_switch_to(struct task_struct *to)
 111{
 112        if ((to->thread.arch.fs == 0) || (to->mm == NULL))
 113                return;
 114
 115        arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
 116}
 117